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linux/arch/arm/mm
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Russell King 2be23c475a ARM: Ensure PTE modifications via dma_alloc_coherent are visible 
Dave Hylands reports:
| We've observed a problem with dma_alloc_writecombine when the system
| is under heavy load (heavy bus traffic).  We've managed to reduce the
| problem to the following snippet, which is run from a kthread in a
| continuous loop:
|
|   void *virtAddr;
|   dma_addr_t physAddr;
|   unsigned int numBytes = 256;
|
|   for (;;) {
|       virtAddr = dma_alloc_writecombine(NULL,
|             numBytes, &physAddr, GFP_KERNEL);
|       if (virtAddr == NULL) {
|          printk(KERN_ERR "Running out of memory\n");
|          break;
|       }
|
|       /* access DMA memory allocated */
|       tmp = virtAddr;
|       *tmp = 0x77;
|
|       /* free DMA memory */
|       dma_free_writecombine(NULL,
|             numBytes, virtAddr, physAddr);
|
|         ...sleep here...
|     }
|
| By itself, the code will run forever with no issues. However, as we
| increase our bus traffic (typically using DMA) then the *tmp = 0x77
| line will eventually cause a page fault. If we add a small delay (a
| few microseconds) before the *tmp = 0x77, then we don't see a page
| fault, even under heavy load.

A dsb() is required after modifying the PTE entries to ensure that they
will always be visible.  Add this dsb().

Reported-by: Dave Hylands <dhylands@gmail.com>
Tested-by: Dave Hylands <dhylands@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-09-08 16:27:56 +01:00
..
abort-ev4.S
abort-ev4t.S
abort-ev5t.S
abort-ev5tj.S
abort-ev6.S Add core support for ARMv6/v7 big-endian 2009-05-30 14:00:18 +01:00
abort-ev7.S arm: mm: qsd8x50: Fix incorrect permission faults 2010-05-03 11:15:05 -07:00
abort-lv4t.S [ARM] nommu: abort handler fixup for !CPU_CP15_MMU cores. 2006-09-28 20:15:46 +01:00
abort-macro.S
abort-nommu.S [ARM] 5227/1: Add the ENDPROC declarations to the .S files 2008-09-01 12:06:34 +01:00
alignment.c ARM: 6268/1: ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault 2010-07-27 10:48:41 +01:00
cache-fa.S ARM: dma-mapping: remove dmac_clean_range and dmac_inv_range 2010-02-15 15:22:23 +00:00
cache-feroceon-l2.c [ARM] Kirkwood: small L2 code cleanup 2009-03-28 22:39:30 -04:00
cache-l2x0.c ARM: 6272/1: Convert L2x0 to use the IO relaxed operations 2010-07-29 14:04:36 +01:00
cache-tauros2.c ARM: Add Tauros2 L2 cache controller support 2009-11-27 15:43:21 -05:00
cache-v3.S ARM: dma-mapping: remove dmac_clean_range and dmac_inv_range 2010-02-15 15:22:23 +00:00
cache-v4.S ARM: dma-mapping: remove dmac_clean_range and dmac_inv_range 2010-02-15 15:22:23 +00:00
cache-v4wb.S ARM: dma-mapping: remove dmac_clean_range and dmac_inv_range 2010-02-15 15:22:23 +00:00
cache-v4wt.S ARM: dma-mapping: remove dmac_clean_range and dmac_inv_range 2010-02-15 15:22:23 +00:00
cache-v6.S ARM: 6188/1: Add a config option for the ARM11MPCore DMA cache maintenance workaround 2010-07-01 10:12:31 +01:00
cache-v7.S ARM: 6139/1: ARMv7: Use the Inner Shareable I-cache on MP 2010-05-20 23:52:38 +01:00
cache-xsc3l2.c [ARM] pxa: do not enable L2 after MMU is enabled 2010-01-01 15:50:34 +08:00
context.c ARM: 5905/1: ARM: Global ASID allocation on SMP 2010-02-15 21:39:51 +00:00
copypage-fa.c ARM: Gemini: fix compiler error in copypage-fa.c 2010-04-27 12:45:10 +02:00
copypage-feroceon.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-v3.c ARM: Pass VMA to copy_user_highpage() implementations 2009-10-05 15:17:45 +01:00
copypage-v4mc.c ARM: Pass VMA to copy_user_highpage() implementations 2009-10-05 15:17:45 +01:00
copypage-v4wb.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-v4wt.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-v6.c ARM: 6007/1: fix highmem with VIPT cache and DMA 2010-04-14 11:11:27 +01:00
copypage-xsc3.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-xscale.c ARM: Pass VMA to copy_user_highpage() implementations 2009-10-05 15:17:45 +01:00
dma-mapping.c ARM: Ensure PTE modifications via dma_alloc_coherent are visible 2010-09-08 16:27:56 +01:00
extable.c [ARM] Convert asm/uaccess.h to linux/uaccess.h 2008-09-06 11:35:55 +01:00
fault-armv.c Merge branch 'devel-stable' into devel 2010-05-17 17:24:04 +01:00
fault.c ARM: 6268/1: ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault 2010-07-27 10:48:41 +01:00
fault.h [ARM] do_bad_area() always takes current and current->active_mm 2006-09-27 16:13:48 +01:00
flush.c ARM: 6007/1: fix highmem with VIPT cache and DMA 2010-04-14 11:11:27 +01:00
highmem.c kmap_atomic: make kunmap_atomic() harder to misuse 2010-08-09 20:44:54 -07:00
init.c Merge branch 'devel-stable' into devel 2010-07-31 14:20:16 +01:00
iomap.c [ARM] Convert asm/io.h to linux/io.h 2008-09-06 12:10:45 +01:00
ioremap.c ARM: use generic ioremap_page_range() 2010-07-27 10:43:47 +01:00
Kconfig ARM: 6344/1: Mark CPU_32v6K as depended on CPU_V7 2010-09-02 15:32:13 +01:00
Makefile ARM: Remove DISCONTIGMEM support 2010-07-16 10:57:35 +01:00
mm.h ARM: Convert platform reservations to use LMB rather than bootmem 2010-07-27 08:48:23 +01:00
mmap.c [ARM] add address randomization to mmap() 2010-06-14 21:22:11 -04:00
mmu.c Merge branch 'misc' into devel 2010-07-31 14:20:02 +01:00
nommu.c ARM: Convert platform reservations to use LMB rather than bootmem 2010-07-27 08:48:23 +01:00
pabort-legacy.S ARM: 5727/1: Pass IFSR register to do_PrefetchAbort() 2009-10-02 22:34:32 +01:00
pabort-v6.S ARM: 5727/1: Pass IFSR register to do_PrefetchAbort() 2009-10-02 22:34:32 +01:00
pabort-v7.S ARM: 5727/1: Pass IFSR register to do_PrefetchAbort() 2009-10-02 22:34:32 +01:00
pgd.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
proc-arm6_7.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm7tdmi.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm9tdmi.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm720.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm740.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm920.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm922.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm925.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm926.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm940.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm946.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1020.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1020e.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1022.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1026.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-fa526.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-feroceon.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-macros.S Merge branch 'devel-stable' into devel 2009-09-12 12:02:26 +01:00
proc-mohawk.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-sa110.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-sa1100.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-syms.c ARM: add size argument to __cpuc_flush_dcache_page 2009-12-14 14:53:22 +00:00
proc-v6.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-v7.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-xsc3.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-xscale.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
tlb-fa.S ARM: Add support for FA526 v2 2009-03-25 13:10:01 +02:00
tlb-v3.S
tlb-v4.S
tlb-v4wb.S
tlb-v4wbi.S
tlb-v6.S arm: Use __INIT macro instead of .text.init. 2009-04-27 19:51:58 -07:00
tlb-v7.S ARM: 6112/1: Use the Inner Shareable I-cache and BTB ops on ARMv7 SMP 2010-05-08 10:44:30 +01:00
vmregion.c ARM: DMA coherent allocator: align remapped addresses 2010-07-27 10:43:48 +01:00
vmregion.h ARM: DMA coherent allocator: align remapped addresses 2010-07-27 10:43:48 +01:00